JPH0225665A - Piston engine, compressor with said piston engine and low-temperature cooler - Google Patents

Abstract

PURPOSE: To provide a piston engine, a compressor and a cryo-cooler having a relatively compact structure which can be manufactured easily by coupling a compression space through an accumulator with an expansion space for containing a reciprocal displacer. CONSTITUTION: A double piston engine constitutes a boxer type compressor and supplies compressed air to a load 129. A cryo-cooled can be obtained by coupling a piping 67 with an expansion unit 131 (load) which drives a displacer 145 with a pressure difference caused by friction. A gas pressure fluctuation occurring in the compression space 65 of a compressor 1 propagates on a part at gaseous working fluid (helium gas) through a piping 67 and a piping 123 in the expansion unit 131. The gas is present in a cooler 137, a refrigerator 139, a freezer 141 and the substantially tubular displacer 145 which is driven by the differential gas pressure and the differential effective area between the opposite sides thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention includes a piston that is reciprocated within a cylinder by a direct-acting electric motor to displace a gaseous medium, and that is moved by at least one dynamic groove bearing. This invention relates to a piston engine that is pivotally supported in the radial direction. The invention furthermore relates to a compression device comprising two piston engines of the above type connected to each other. The invention further relates to a cryogenic cooler comprising a piston engine of the type described above.

BACKGROUND ART Unpublished Dutch patent application no. 8800055 discloses a piston engine, a compression device, and a cryocooler of the type mentioned at the beginning of the text. In this case, the piston engine forms part of the compression device of the cryogenic cooler.

In such piston engines, the electric direct drive motor is located between two dynamic groove bearings, resulting in a relatively large length structure.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a piston engine, a compression device, and a low temperature cooler that are relatively easy to manufacture and have a relatively compact structure.

(Disclosure of the Invention) In order to achieve the above object, the piston engine of the present invention has a piston supported by a dynamic groove bearing on a cylindrical outer surface of a guide concentric with the piston and a cylindrical inner surface located inside the piston. The groove bearing is characterized in that it is separated from the compression space adjacent to the 14 faces of the piston by a cylindrical sealing gap with an annular cross section.

No. 4,697,113 discloses a piston engine, a compression device and a cryocooler individually as well as in combination. However, the known piston engines are constructed in such a way that the compression device and the cryocooler can be moved directly in the cylinder without being particularly radially supported.

A preferred embodiment of the piston engine, in which the radial support of the piston engine is provided by a relatively small number of components, is characterized in that the guide concentric with the piston is a fixedly arranged mandrel inserted into the piston.

Another embodiment of a piston engine with a rotary motor integrated into a compact structure is such that the piston can be rotated by an electric rotary motor around a fixedly arranged mandrel, the stator coil of said motor being connected to the inner wall of a chamber in the fixedly arranged mandrel. The permanent magnet rotor of the rotary motor is fixed to the rotary motor and is located on a support, which support is connected to the piston and extends into the stator coil within the chamber of the mandrel.

Another embodiment of the piston engine, in which dynamic groove bearings can be produced relatively easily, is characterized in that at least one dynamic groove bearing groove pattern is provided on the cylindrical outer surface of the mandrel, which serves as a guide for the piston. .

A compression device of compact construction, which is easy to manufacture, comprises two piston engines according to the invention, the compression space being limited on both sides by the piston ends of said piston engines and connected to the load.

A cryogenic cooler of compact construction, which is easy to make and which includes a piston engine or compression device according to the invention, is characterized in that the compression space is connected with respect to a regenerator to an expansion space that accommodates a reciprocating displacer. .

(Example) The invention will be explained with reference to the drawings.

The device 1 shown in FIG. 1 is symmetrical with respect to line 3 and consists of two identical piston engines 5.7 according to the invention. This device acts as a compression device, which can be expanded into a compressor as shown in FIG. 2 or integrated into a cryocooler as shown in FIG. 3.4. The piston engines 5, 7 located on either side of the line 3 in FIG. 1 can each be expanded separately into a so-called single-piston compressor. The multi-piston engine shown in FIG. 1 can be thought of as a so-called "boxer" type compressor. The piston engines 5 and 7 are connected to each other by a connecting ring 9 and a bolt 11. The reciprocating piston 13.15 has two respective piston engines 5.7
a cylindrical tube 17.19 and a bottom 2 connected thereto;
Consists of 1.23. Piston 13.15 is cover 2
9.31 Each housing closed by 25.27
Place it inside. A cylindrical sleeve 33.35 made of cobalt iron, for example, is fixed to the piston 13.15. Each sleeve 33,35 is made of samarium cobalt, for example.
serves as a support for the respective annular permanent magnets 37, 39 and 41.43. Permanent magnets 37.39 and 41.4
3 are free to move along the cylindrical inner wall of the roll (45 and 47, respectively). Coils 49.51 and 53.55 are fixed to said windings, which are for example cobalt iron sleeves 57.
．． Enclose within 59. Sleeve 33.35, radially magnetized permanent magnet 37.39°41, 43, coil 49
．． The two assemblies constituted by the sleeves 51, 53, 55 and the sleeves 57, 59 act as a brushless direct current motor 61, 63 for the direct movement of the pistons 13, 15. Between the bottom (end faces) 21, 23 of the piston 13, 15 there is a compression space 65 filled with a gaseous working medium, for example helium. Space 65 is connected to one device by a conduit 67. This device, together with the compression device 1, constitutes a low temperature cooler, which will be explained with reference to FIG. 3.4.5.

The coupling ring 9 is provided with a radial duct 69 for connection to a lead wire 67.

Cover 29. ．． 31 comprises a cylindrical mandrel in the form of a cylindrical guide (71.73 respectively) for the pistons 13.15. The guide 71.73 is the piston 13. 15 concentrically. Piston 13. 15 and guidance 71.
The centerline of 73 coincides with the centerline 75 of device 1 . Guided by fishbone groove patterns 77, 78, 79, 80 forming a radially acting pair of dynamic groove bearings (71, 73 respectively)
on the cylindrical outer surface of. inserted into the piston 13.15,
A fixedly arranged guide 7173 in the form of a mandrel has a coil 81 fixedly arranged near the end facing the bottom 21.23.
, 83. Inside the coil 81.83 is an annular radially magnetized permanent magnet 85. made of samarium cobalt.
87, these magnets are fixed by cobalt iron rings 89.91 on tubular supports 93.95, said supports being integral with the bottom 21.23. The coils 81, 83 are enclosed within cobalt iron sleeves 97,99.

The two assemblies formed by the sleeve 97.99, the gear 81.83, the multipolar permanent magnet 85.87 and the ring 89.91 act as a brushless direct current rotary motor 101.103 for the rotation of the piston 13.15. do. Said motor is necessary to form a dynamic gas radial bearing in the area of groove patterns 77, 78, 79, 80. The piston 13.15 is free to move along the inner wall of the sleeve 105.107 which is fixed to the inner wall of the housing 25.27. Sleeve 105. 107 and piston 13. 15
An intervening cylindrical annular sealing gap 109,111 is between the compression space 65 and the associated pair of dynamic groove bearings. Since the location of the annular sealing gap 109, 111 and the location of the corresponding pair of dynamic groove bearings are far from each other, a relatively large gap width of 25 μm is sufficient in the area of the sealing gap in this example. A desired seal is obtained with a sealing gap of appropriate length. The distance between the inner and outer seals and bearings of the piston allows for a relatively large sealing gap. This is because in this case a dynamic groove bearing is arranged in the direct drive motor 61,63. Nevertheless, a compact structure is obtained in the direction parallel to the centerline 75 compared to a structure in which the linear motor is placed between two dynamic groove bearings with adjacent sealing gaps. Mokuro 1.63
The space around the guide 71.73 and the space within the guide 71.73 communicate with each other through radial ducts H13, 115. This provides a relatively large space in which the reciprocating movement of the piston 13.15 causes only small fluctuations in the average pressure level.

This is advantageous for optimizing the operation of the dynamic groove bearing. Chamber 1 of the guide or mandrel (71, 73)
The support 93.95 of the rotary motor 101.103 extending into 17.119 makes it possible to obtain a very compact construction with only a few components.

Depending on the use of the compression device of FIG. 1 with a double-piston engine, the duct 69 is closed with a so-called valve cover and the
．． It is connected to a device as shown in FIG.

As can be seen in FIG. 2, which has the same reference numerals as in FIG. The multi-piston engine of FIG. 2 constitutes a boxer compressor and supplies compressed air to the illustrated load 129. When the pipe line 67 is connected to the expansion device 131 (load) shown in FIG. 5, a low temperature cooler shown in the top view in FIG. 3 and in the side view in FIG. 4 is obtained. It should be noted that this does not exclude that the intended "load" on the expansion device 131 always involves the same confined volume of working medium. Fluctuations in gas pressure occurring within the compression space 65 of the compression device 1 shown in FIG.
and is transmitted to a portion of the gaseous working medium (helium gas) via the line 123 in the expansion device 131. This gas is present in a cooler 137, a refrigerator 139, a freezer 141, and a substantially cylindrical displacer 145. The displacer is driven by the gas pressure difference and the difference in effective area on each side of the displacer. The upper side of the expansion space 143 is the cover 1
47 and the cover is screwed onto the tube 149 which has threads on both ends. The lower side of the tube 149 is screwed into the ring 151,
The ring is fixed to a holder 155 for a heat exchanger 157. This heat exchanger forms part of cooler 137. The holder 155 is a duct for supplying and discharging cooling liquid [59, 16
1. The housing 165 is fixed to the holder 155 with bolts 163. The expansion device 131 is closed on its lower side by a second cover 167. The second cover is secured to the housing 165 by a pin 169.

The housing 165 accommodates a cylindrical guide 171 to which a holder 173 for a rotary motor 175 is fixed.

The motor 175 is a brushless DC motor whose rotor magnet 177 is fixed to a rotary tube 179 which is rotatably supported in a guide tube 181 surrounded by a sealing gap 180. The bottom 183 of the displacer 145 is integral with the guide tube 181. The rotating tube 179 is the expansion device 131
A shaft 187 fixed in a direction parallel to the center line 185 of
to accommodate. The rotating tube 179 has two dynamic groove bearings 189
．． 191 to be pivotally supported on the shaft 187.

The fishbone groove pattern of the bearing is located on the shaft 187. Furthermore, the rotary tube 179 has two dynamic groove bearings 1
93 . In order to achieve a compact structure, the upper part 181a of the guide tube 181 is placed inside the displacer 145, and the lower part 181b is placed outside the displacer. The centerline 185 of the expansion device 131 is aligned with the displacer 145. Guide tube 181, rotating tube 179
and coincides with the centerline of shaft 187.

The low-temperature cooler of the present invention is not limited to a cooler including an expansion device 131 as shown in FIG. 5 in which the displacer 145 is driven by a pressure difference caused by friction. The displacer 145 also has its own drive and may be driven, for example, by an electric motor. The linear magnet of this electric motor is connected to the guide tube 181. In this regard, applicant's Dutch patent application No. 880005
You can refer to No. 5. The structures of the low-temperature cooler, compression device, and piston are compact, have a very small number of parts, and are relatively easy to manufacture, which is very advantageous. Pivoting the rotary/linear piston with dynamic groove bearings provides a very long service life, which allows the piston engine to be used in areas such as, for example, cooling of computer processors. In this case, the processor is located in a cryogenic chamber, and its cooling liquid is kept at a cryogenic temperature (eg, 77 K) by a cryogenic cooler as described above.

Piston 13. 15 may be arranged so as not to rotate. In this case, the piston 13.
15 and guides 71, 73 may be used which are radially supported by dynamic groove bearings.

In this regard, reference may be made to the above-mentioned Dutch patent application.

The compression device according to the present invention can be used for a piston engine according to the present invention.
You may have only one.

Although the present invention has been described with respect to piston engines, compression devices, cryogenic coolers, etc. having pistons radially supported by pairs of dynamic groove bearings, single-mounted pistons may also be used. In this case, the piston of the piston engine is radially supported by only one dynamic groove bearing. Whether such a single bearing is possible depends on the piston engine, and in particular on the piston length.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a multi-piston engine according to the present invention, FIG. 2 is a vertical cross-sectional view of a compressor according to the present invention, FIG. 3 is a plan view of a low-temperature cooler according to the present invention, and FIG.
FIG. 5 is an enlarged sectional view of a part of the low temperature cooler shown in FIGS. 3 and 4. FIG. 5.7...Piston engine 9...Connection ring 11
...Bolt 13.15...Reciprocating piston 17, 19...Cylindrical tube 21.23...
・Bottom 25, 27...Housing 29.31...
- Covers 33, 35...Sleeves 37, 39.41.43...Permanent magnets 49, 51.
53. 55...Coil 57, 59...Sleeve 61.63...Direct drive motor 65...Compression space 67...Pipe line 71, 73...Guide 78, 79.80...Fish bone Shape groove pattern 83...
Coil 85.87...Permanent magnet 91...
Ring 101. 103...Rotating motor 1
07... Sleeve 111... Annular sealing gap 115... Radial duct) 117. 119...
Chamber... Valve cover 125... Pressure valve... Suction valve 129... Load... Expansion device 137... Cooler... Freezer
141... Freezer... Expansion space
145...Displacer...Cover
149...Tube...Heat exchanger 175...
・Rotating motor...Rotor magnet 179...Rotating tube 195...Dynamic groove bearing

Claims (1)

[Claims] 1. A piston, the piston being reciprocated within a cylinder by a direct-acting electric motor to move a gaseous medium;
and is journalled radially relative to the direction of piston movement by at least one dynamic groove bearing, wherein the piston is located within the piston on a cylindrical outer surface of a guide concentric with the piston by the dynamic groove bearing. A piston engine which is journalled on a cylindrical inner surface and characterized in that the dynamic groove bearing is separated from the compression space adjacent to one end face of the piston by a cylindrical sealing gap with an annular cross section. 2. A piston engine according to claim 1, wherein the guide concentric with the piston is a fixedly arranged mandrel inserted into the piston. 3. The piston is rotatable around a fixedly arranged mandrel by an electric rotating motor, the stator coil of said motor is fixed to the inner wall of the chamber in the fixedly arranged mandrel, and the permanent magnet rotor of the rotating motor is located on the support. 3. The piston engine of claim 2, wherein the support is connected to the piston and extends into the stator coil within the chamber of the mandrel. 4. Piston engine according to claim 3, characterized in that the groove pattern of at least one dynamic groove bearing is provided on the cylindrical outer surface of the mandrel serving as a guide for the piston. 5. A compression device comprising two piston engines connected to each other according to any one of claims 1 to 4, wherein the compression space is limited on both sides by the piston ends of the piston engines and is connected to a load. . 6. A low-temperature cooler comprising the piston engine according to any one of claims 1 to 4, wherein the compression space is connected to the expansion space accommodating a reciprocating displacer via a heat storage device. 7. A low-temperature cooler comprising the compression device according to claim 5, wherein the compression space is connected to the expansion space accommodating a reciprocating displacer via a heat storage device.